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Lui, Mei-ki Pattie. "Acceptor defects in P-type gallium antimonide materials." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31648368.
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Lui, Mei-ki Pattie, and 雷美琪. "Acceptor defects in P-type gallium antimonide materials." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31648368.
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Dawnay, Emma J. C. "Characterisation of organic-donor-#pi#-acceptor materials for nonlinear optics." Thesis, Cranfield University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305248.
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Teng, Teng. "Semiconducting Materials Based on Donor/Acceptor Units for Optoelectronic Applications." Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS452.pdf.
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Les semi-conducteurs cristaux liquides et les matériaux à faible gap sont deux familles de matériaux intéressants pour des applications dans le domaine de l’optoélectronique. Ils peuvent être utilisés dans de nombreux dispositifs électroniques différents tels que les cellules solaires organiques (OPV), les diodes électroluminescentes organiques (OLED) et les transistors organiques à effet de champ (OFET). Dans ce travail, nous nous sommes concentrés sur la conception et la synthèse de nouveaux matériaux semi-conducteurs constitués d’architectures donneur / accepteur qui présentent soit des propriétés de photoluminescence et de transport de charge élevées, soit un gap énergétique fable pour viser des matériaux ambipolaires. Les premières séries de matériaux sont des molécules organiques cristal liquides basées sur un cœur accepteur de benzothiadiazole et des groupes donneurs de type alcoxyphényle, avant de développer des structures plus complexes de type diade et triade. Les molécules à faible gap sont quant à elles constituées d’un cœur naphtalène diimide substitué par des unités comportant le benzothiadiazole. L'objectif était d'étudier leurs propriétés photophysiques, leurs propriétés de transport de charge et de corréler ces propriétés avec les propriétés structurelles des matériaux développés. Sur la base de nos résultats, nous avons démontré que ces molécules luminescentes possèdent des propriétés cristal liquide avec des structures lamellaires ou multilamellaires constituées de couches alternées d'unités fluorescentes ? Ces matériaux possèdent également une capacité élevée à transporter des charges, ce qui indique que ces composés ont un potentiel intéressant pour des applications en optoélectronique et en particulier pour des dispositifs type OFET. D’autre part, il a été démontré que les deux molécules à faible gap possèdent des propriétés de transport de charge de type n ou de type ambipolaireLiquid crystalline semiconductors and narrow bandgap materials are two kinds of interesting materials for optoelectronic applications. They can be used in several type of organic electronic devices such as organic solar cells (OPV), Organic Light Emitting Diodes (OLED) and Organic Field Effect transistors (OFET). In this work, we focused on designing and synthesizing novel semiconducting materials based on donor/acceptor architectures which present either high photoluminescence and charge transport properties, or a narow bandgap for ambipolar charge transport. These materials are liquid crystalline molecules based on a benzothiadiazole acceptor core and alkoxyphenyl donor groups. The narrow bandgap molecules are based on a naphthalene diimide core and in this case flanked by benzothiadiazole units. The objective was to study their photophysical properties, charge transport properties, and to correlate this to the structural properties of the materials developed. Based on our results, we demostrated that these luminescent molecules possess liquid crystal properties with lamellar or multi-lamellar structures consisting of alternating layers of fluorescent units and high charge transport moieties. The charge transport properties measured of these compounds indicate that they have a potential for optoelectronic applications such as OFET devices. In addition, the two narrow bandgap molecules developed were found to exhibt n-type, and ambipolar charge transport properties
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Schmitt, Jennifer [Verfasser]. "Investigation of acceptor dopants in ZrNiSn half-Heusler materials / Jennifer Schmitt." Mainz : Universitätsbibliothek Mainz, 2015. http://d-nb.info/1068048344/34.
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Berlie, Adam. "A study of magnetic materials based upon the organic acceptor 7,7,8,8-tetracyanoquinodimethane." Thesis, Durham University, 2013. http://etheses.dur.ac.uk/6912/.
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The study of organic based materials is a flourishing area of interest as the physical/chemical properties of the compound can be tuned through functionalisation or simple chemical changes to the organic component. This thesis will focus on the magnetic behaviour of metal-organic magnetic materials where a variety of techniques will be used to study the magnetism such as bulk magnetometry and muon spin relaxation. As well as the magnetic properties, some comments will be made on the chemical properties such as molecular structure. The thesis begins with an overview of the theory of magnetism and details regarding experimental techniques. Ni(TCNQ)$_2$ is a recently discovered non-solvated metal organic magnet that was reported to show ferromagnetic behaviour below 20 K where there was evidence of a glassy magnetic component. This thesis reports the synthesis of both a protio and deutero form of the material where upon deuteration of the TCNQ molecule, a shift in critical temperature ($T_{\rm C}$) was observed to a higher temperature by approximately 15%. Diffraction experiments were conducted to attempt to provide information on the atomic structure however this proved unsuccessful. Magnetometry experiments showed a ferromagnetic transition at approximately 20 K in the deuterated and 17 K in the protonated materials where at low temperatures the sample appeared to be a three-dimensional magnetically order material. Muon spin relaxation studies were conducted on the deuterated sample which showed two peaks within the dynamical relaxation in zero-field; one associated with the transition and a low temperature (5 K) spin freezing effect where it is believed there are interactions between magnetic clusters that enter a quasi-static regime. It may be possible that the glassy component and the ferromagnetic behaviour of the material are not due to the same exchange mechanism or magnetic interactions. KTCNQ is a compound that undergoes a spin-Peierls transition, $T_{\rm SP}$, at approximately 400 K where below this temperature there is a dimerisation of the TCNQ radical spins that couple antiferromagnetically and the system goes from a conductive to insulating state. In an attempt to tune the TCNQ-TCNQ interactions different materials were synthesised where the protons on the TCNQ ring were substituted for fluorine and bromine atoms. On substitution of the protons with other elements a dramatic shift in Tsp was observed where for the fluorine based compounds $T_{\rm SP}$ = 150 K and the KTCNQ-Br$_2$ compound showed no evidence of a transition. Both KTCNQ-H$_4$ and KTCNQ-F$_4$ were studied further using muon spin relaxation where the transition is clearly modelled using a stretched exponential where an increase in electronic fluctuation rate is shown by a gradual move from an exponential to Gaussian relaxation. At low temperatures the relaxation again changes and within the KTCNQ-F$_4$ sample 2 F-$\mu^+$-F states are observed. Another controversial organic based magnet is Ni$_2$TCNQ which was first synthesised in 2007. Here a study of a similar material is reported where the TCNQ has been swapped for TCNQF$_4$ and the magnetic properties are shown to be a result of nickel nanoparticles trapped within a metal-organic or purely organic based matrix. The room temperature ferromagnetism is not strictly due to only the bulk Ni particles as this would result in a blocking temperature below 20 K and so the matrix is shown to play an important role. The size of the Ni nanoparticles was shown to be tuneable when using different solvents within the reaction, generally use of chlori- nated solvents lead to rapid decomposition of the starting material, Ni(COD)$_2$ and lead to larger nanoparticles, however use of a nitrile based solvent led to Ni clusters that were approximately 1 nm in size and dispersed within the matrix. A novel scaling of the magnetisation curves as a function of field showed that once the ferromagnetic component had been subtracted the matrix or Ni based clusters show an antiferromagnetic ground state at low temperature. The final chapter describes an investigation of the starting material, Ni(COD)$_2$ which was studied using a SQUID magnetometer where it was shown that there was a high level of magnetic impurities, which was attributed to small Ni clusters that showed a similar scaling relationship of the magnetisation as for the Ni2TCNQF$_4$ based material. This demonstrates the inappropriate nature of Ni(COD)$_2$ as a starting material for metal-organic based magnetic compounds.
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Hsu, Yu-Te. "Comparative Study of APFO-3 Solar Cells Using Mono- and Bisadduct Fullerenes as Acceptor." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57796.
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The urgent need for new, sustainable energy source intrigues scientists to provide the solution by developing new technology. Polymer solar cell appears to be the most promising candidate for its low cost, flexibility, and massive producibility. Novel polymers have been constantly synthesized and investigated, while the use of PCBM as acceptor seems to be the universal choice. Here, we studied the use of four dierent fullerene derivatives - [60]PCBM, [70]PCBM, and their bisadduct analogues - as acceptor in APFO-3 solar cells. A series of investigations were performed to study how the processing parameters - blend ratio, spin speed, and choice of solvent - influence the device performance. Using bisadduct fullerenes results in an enhanced Voc, as predicted by the up-shift of energy levels, but a strongly reduced Jsc, hence a poor PCE. Photoluminescence study indicates that all APFO-3:fullerene devices are limited by the inefficient dissociation of fullerene excitations, while it becomes more influential when bisadduct fullerenes were used as acceptor. The best device in this study was fabricated by using [70]PCBM as acceptor and chlorobenzene as solvent, exhibits a PCE of 2.9%, for the strong absorption, ne morphology, and comparatively strong driving force.
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Foote, Anna L. "Investigation of Solvent-Dependent Properties of Donor and Acceptor Materials for Photovoltaic Applications." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1438774794.
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Ikeda, Jeri Ann Sachie. "Grain boundary defect chemistry and electrostatic potential in acceptor- and donor-doped titanium dioxide." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/13233.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1992.Includes bibliographical references (leaves 142-145).
by Jeri Ann Sachie Ikeda.
Ph.D.
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Berhe, Seare Ahferom. "Acceptor-sensitizers for Nanostructured Oxide Semiconductor in Excitonic Solar Cells." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699927/.
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Organic dyes are examined in photoelectrochemical systems wherein they engage in thermal (rather than photoexcited) electron donation into metal oxide semiconductors. These studies are intended to elucidate fundamental parameters of electron transfer in photoelectrochemical cells. Development of novel methods for the structure/property tuning of electroactive dyes and the preparation of nanostructured semiconductors have also been discovered in the course of the presented work. Acceptor sensitized polymer oxide solar cell devices were assembled and the impact of the acceptor dyes were studied. The optoelectronic tuning of boron-chelated azadipyrromethene dyes has been explored by the substitution of carbon substituents in place of fluoride atoms at boron. Stability of singlet exited state and level of reduction potential of these series of aza-BODIPY coumpounds were studied in order to employ them as electron-accepting sensitizers in solid state dye sensitized solar cells.
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Spitler, Eric Lewis 1980. "Structure-property relationships in conjugated donor/acceptor-functionalized arylacetylenes and dehydrobenzoannulenes." Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/8095.
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xx, 361 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.Highly conjugated carbon-rich molecules have attracted interest in recent years due to unique electronic, optical and materials properties. Carbon networks based upon the phenylacetylene subunit are increasingly recognized as building blocks for a host of sensing and electronics components due to the rigidity and linearity of carbon-carbon triple bonds. Further extending this motif into a macrocycle, generating a dehydrobenzoannulene (DBA), also confers planarity, increasing the à -conjugation and giving rise to enhanced materials behavior. Functionalization of arylacetylenes and DBAs with electron donating and accepting groups manipulates the energetics such that finely-tuned optoetectronic properties can be devised for customized applications, including fluorescent sensor arrays, organic light-emitting diodes, and nonlinear optical materials. Fundamental structure-property relationship studies into certain physical modifications of molecular architecture effects on the photophysics, intramolecular charge transfer (ICT), or complexation properties are of importance in the rational design of the next generation of organic electronics. Chapter I provides a review of recent advances in the field of annulene chemistry. It is organized by cycle type, size, and application within each category. Chapter II describes syntheses and ion responses of an array of donor/acceptor-functionalized arylacetylenes. The independent manipulation of frontier molecular orbital (FMO) energy levels is discussed in relation to a fluorescent switching phenomenon. Chapter III expands this effect to include [15]DBAs. The consequences of incorporating protonatable donor/acceptor groups into a macrocycle, as well as placement of the acceptor nitrogen are examined, and comparison of calculations to experimental results imply generation of transient ICT species with induced FMO localizations. Chapter IV describes the syntheses of acyclic tetrakis(phenylethynyl)benzene (TPEB) and [14]- and [15]DBA systems utilizing fluorinated acceptor groups. Comparisons between these inductive acceptors and earlier resonance acceptors are made, and imply greater stability and processing potential for optoelectronic applications. Chapter V describes a series of bis[18]DBAs functionalized with dibutylamino groups as donors and nitro groups as acceptors. The effects of 2-donor/2-acceptor versus 4-donor/4-acceptor motifs are explored, and trends are identified in the systematic adjustment of the optical band gap that will have important implications for the design of two-photon absorbing materials. This dissertation includes my previously published and co-authored material.
Adviser: Michael M. Haley
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Durmus, Asuman. "Realization Of Neutral State Green Polymeric Materials." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610738/index.pdf.
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Polymeric electrochromic materials that has as one of the three complementary colors (red, green, and blue) in the neutral form and become transparent via oxidation (or reduction), has a crucial importance towards use of these materials in electrochromic devices and displays. To reflect red or blue color in neutral state, the materials have to absorb at only one dominant wavelength. On the contrary, to have a green color, there should exist at least two simultaneous absorption bands in the red and blue regions of the visible spectrum where these bands should be controlled with the same applied potential. The transmissivity in the oxidized state is significantly important in addition to the neutral state color of the polymer. The optical contrast between the states is the decisive point for use of these materials for many electrochromic applications, especially as smart windows and displays. Hence, the material should possess two absorption bands with definite maximum points, and upon oxidation these bands should simultaneously vanish to have a transmissive state. A donor&ndashacceptor approach can be utilized to solve this puzzle. It has been shown that insertion of alternating donor&ndash
acceptor units on the polymer backbone leads to a significant decrease in band gap due to the increased double bond character in the structure. In this study novel donor-acceptor type polymers were synthesized, and electrochromic properties were investigated in detail. PBDT is the first green electrochromic material which has a highly transmissive sky blue oxidized state. PDETQ was shown to be one of the few examples of neutral state green polymeric materials in literature. PDEQ has a bluish green color in the neutral state and a highly transmissive light blue oxidized state.
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Manda, Venkata Ramana. "Enhancing the Photovoltaic Performance of P3HT/PDIB Silsesquioxane Donor-Acceptor System Using Spray Deposition Fabrication Technique." TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1336.
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In the past few years, the solution-processed organic based solar cells gained more importance by meeting the demands for cost effective photovoltaic devices. To date, the focus of the organic photovoltaic devices has been on the optimization of the processing the materials to improve photo conversion efficiency and also by modifying the active components of the organic materials. Recently, it has been recognized that the deposition techniques also plays a major role in enhancing the power conversion efficiencies. Currently, though the most common deposition technique for organic solar cells is spin coating, which does not allow scaling up of the large device area. As an alternative method, a simple airbrush spray deposition technique has been developed to fabricate the test devices. The film thickness of the layers was characterized under scanning electron microscope. Devices with different thickness (1000 nm, 500 nm, 240 nm) of poly(3,4-ethylenedioxythipohene) polystyrene sulfonate (PEDOT.PSS) and active layers are prepared and their photovoltaic performances have been evaluated and compared by plotting the IV curves with respect to each thickness. Maintaining the distance between the substrate and the airbrush nozzle the thickness of the layers was controlled. From the results, we found that the test devices with 500 nm thickness of PEDOT.PSS and active layers shows the best device performance with highest current density of 3.97 mA/cm2, open circuit voltage of 1.3 V and power conversion efficiency of 2.34%. As a control experiment, devices were also developed using the standard poly(3- hexylthiophene-2,5-diyl):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) system, but the power conversion efficiencies of these devices were not promising with respect to the literature results. Future studies of this project will focus on improving the power conversion efficiency of poly(3-hexylthiophene-2,5-diyl)/perylenediimide bridged system (P3HT/PDIB) by developing a new device architecture called “tandem solar cells” which consists of multiple layers of different donor and acceptor blends with inorganic transition metal oxides such as zinc oxide and molybdenum oxides.
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Linton, Katharine Elizabeth. "New bipolar organic materials for optoelectronic applications." Thesis, Durham University, 2012. http://etheses.dur.ac.uk/4437/.
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The literature surrounding organic small-molecule donor-acceptor systems is summarised for a range of optoelectronic applications (OLEDs, OPVs, OFETs etc.). There is a focus on the key building blocks: 1,3,4-oxadiazole (OXD), diphenylamine (DPA), carbazole (Cbz) and fluorene (F). The incorporation of such moieties into various donor-acceptor systems is discussed with further reference to selected alternative organic donor and acceptor systems. The syntheses of novel bipolar molecules based on a donor-spacer-acceptor (DPA/Cbz-F-OXD) structure and the incorporation of these molecules into single-layer OLEDs is presented. It is demonstrated how the emission colour can be tuned from green to deep blue by systematic manipulation of the structure. A significant result is that high efficiency accompanied with pure, deep blue emission in single-layer OLEDs can be achieved with this structural motif. The incorporation of these materials as part of a simple two-component blend to produce white OLEDs is presented and the modification of the materials to improve electron-transport properties is discussed. The synthesis of DPA-bridge-OXD wire systems is presented with the use of oligo-p-phenyleneethynylene units as a bridge of varying length to investigate the effect on charge transfer between the donor and acceptor. Photophysical studies demonstrate the change in absorption, emission and fluorescence lifetimes as the length scale of the molecules is altered. The synthesis of a series of planarised and twisted DPA-bridge-OXD systems based upon phenylene linkers is discussed. Finally, a series of DPA-F-OXD-anchor molecules is presented for incorporation into DSSC devices. The synthesis of these materials is described and the suitability of various anchoring groups for DSSCs is analysed through photophysical and device studies.
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Balan, Abidin. "Synthesis Of Benzotriazole Bearing Donor Acceptor Type Electroactive Monomers Towards High Optical Contrast And Fast Switching Electrochromic Materials." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610601/index.pdf.
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Synthesis of new electroactive monomers are highly desired since these compounds can be
utilized as active layers in many device applications such as ECDs, LEDs and solar cells.
EDOT (3,4 ethylenedioxythiophene) and thiophene bearing polymers were also proven to be
excellent candidates as electrochromic materials. Benzotriazole can be coupled to EDOT and
thiophene to yield materials that can be polymerized to give donor acceptor type polymers.
These materials are promising candidates as components in fast switching polymeric
electrochromic devices. Donor acceptor type materials2-dodecyl-4-(2,3-dihydrothieno [3,4- b][1,4]dioxin-5-yl)-7- (2,3-dihydrothieno[3,4-b] [1,4] dioxin-7-yl)-2H-benzo [d][1,2,3]triazole and 2-dodecyl-4,7-di(thiophen-2-yl)-2H-benzo[d][1,2,3]triazole were synthesized via N-alkylation, bromination, stannylation and Stille coupling reactions. Electrochemical and electrochromic properties of the polymers were examined in detail.
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Reckers, Philip [Verfasser], Wolfram [Akademischer Betreuer] Jaegermann, and Thomas [Akademischer Betreuer] Riedl. "Electronic properties of titania (and AZO) and its interface to organic acceptor materials / Philip Reckers ; Wolfram Jaegermann, Thomas Riedl." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/1188410091/34.
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Ekhagen, Sebastian. "Stability of electron acceptor materials for organic solar cells : a work function study of C60/C70 derivatives and N2200." Thesis, Karlstads universitet, Institutionen för ingenjörsvetenskap och fysik (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-72727.
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Thin films of the fullerenes PC60BM and PC70BM and the non-fullerene N2200, three popular electron acceptor materials in organic photovoltaics, have been studied, using both the Kelvin probe method as well as ultraviolet photoelectron spectroscopy. With these methods the work function was measured, as well as the highest occupied molecular orbital (HOMO) onset. Additionally band bending effects were studied by illuminating the samples while measuring the work function with the Kelvin probe so called surface photovoltage. Sample of each material was exposed to either air and simulated sunlight or N2 and simulated sunlight, for different length of time, to observe how the materials work function evolves after exposure to the different conditions. It was observed that, as expected from previous studies, that PC60BM was less photo-stable than PC70BM. Additionally, the work function of PC60BM changed significantly by storage in N2. Each material after exposure for 24h to air and light, was annealed and measured with the Kelvin probe. A restoring effect was observed, for the non-fullerene material N2200. All three materials developed an increasing surface photovoltage, which suggest increased band bending, when exposed to air and light, indicating that due phot-oxidization, charges are redistributed at the surface of the film. The fullerenes showed a larger surface photovoltage effect than the non-fullerene materials. A difference between the work function values obtained from the Kelvin probe method and the ultraviolet photoelectron spectroscopy could be seen, however the exact reason for this couldn't be isolated within this thesis, but was discussed.
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Gunbas, Gorkem E. "Novel Donor-acceptor Type Polymers Towards Excellent Neutral State Green Polymeric Materials For Realization Of Rgb Based Electrochromic Device Applications." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12609002/index.pdf.
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Polymers having one of the three complementary colors (red, green, and blue) in the reduced state and high transmissivity in the oxidized state are key materials towards use in electrochromic devices and displays. Although many neutral state red and blue polymers were reported up to date, neutral state green polymeric materials appear to be limited. For potential application of electrochromic materials in display technologies, one should have to create the entire color spectrum and this can be only achieved by having materials with additive or subtractive primary colors in their neutral states. To obtain a green color there should be at least two simultaneous absorption bands. Although the neutral state color is of great importance, the transmittance in the oxidized state is crucial too. The materials having one of the three primary colors should also possess highly transmissive oxidized states in order to be used in commercial electrochromic device applications. Donor-acceptor molecules lead to lower band gap due to resonances that enable a stronger double bond character between the donor and acceptor units. The materials with low band-gaps produce cathodically coloring polymers due to the lower energy transition in the doped state. Moreover, donor-acceptor type materials commonly show two absorption maxima. Since donor-acceptor approach seems to be the key to the complex nature of producing these materials, novel donor-acceptor type polymers were synthesized, and electrochromic properties were investigated in detail.Additionally a solution-processable donor-acceptor type polymer was realized using method of introducing alkyl side chains in the polymer structures.
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Neubig, Anne [Verfasser], and Mukundan [Akademischer Betreuer] Thelakkat. "Structure-Property Correlation as a Function of Donor and Acceptor Arrangement in Low Band Gap Materials / Anne Neubig. Betreuer: Mukundan Thelakkat." Bayreuth : Universität Bayreuth, 2014. http://d-nb.info/1060009935/34.
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Pandey, Laxman. "Theoretical studies of the structure-property relationships of hole- and electron-transport materials for organic photovoltaic applications." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/48964.
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Donor-acceptor and thiophene based π-conjugated molecules and polymers, along with fullerene derivatives, are extensively used active components in the photoactive layer of organic photovoltaic devices. In this dissertation, we make use of several computational methodologies to investigate structure-property relationships of these organic systems in their molecular forms. We begin with an overview of the field of organic photovoltaics and some of the important problems in organic solar cells that are currently being investigated. This is then followed by a brief review of the electronic-structure methods (e.g. Hartree-Fock theory, Density Functional Theory, and Time-dependent Density Functional Theory) that are employed.
We then present the main results of the dissertation. Chapter 3 provides a broad overview on how changes to the donor-acceptor copolymer chemical structure impacts its intrinsic geometric, electronic, and optical properties. Chapter 4 focuses on the characterization of the lowest excited-states and optical absorption spectra in donor-acceptor copolymers. In Chapter 5, we investigate the effects of alkyl side-chain placements in the π-conjugated backbone of oligothiophenes and how that impacts their intramolecular properties as well as the oligomer:fullerene interfacial interactions. Chapter 6 presents our investigation on the role of oligomer:fullerene configuration and reorganization energy on exciton-dissociation and charge-recombination processes. Finally, a synopsis of the work and further considerations are presented in Chapter 7.
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Raleie, Naledi. "Chromium and Titanium based Stannum Nanocomposites materials as electron acceptors for next generation bulk Heterojunction photovoltaic cells." University of the Western Cape, 2018. http://hdl.handle.net/11394/6398.
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Philosophiae Doctor - PhD (Chemistry)Renewable energy has become the centrepiece of research in resolving the energy crisis. One of the forms of renewable energy is solar energy. This form of energy is costly to develop. Organic molecules are promising materials for the construction of next generation photovoltaic cells considering their advantage of lower cost compared to crystalline silicon that is currently used in solar cells. This forms the basis of this research, which focused on the synthesis and characterisation of poly(3- hexylthiophene) P3HT, stannum (Sn) nanoparticles and stannum-based bimetallic stannum-titanium (SnTi), stannum-chromium (SnCr) and stannum-vanadium (SnV) nanoparticles for the application in the construction of heterojunction photovoltaic cells (PVCs).
2021-12-31
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Liyanage, Arawwawala Don T. "FLUORINATED ARENE, IMIDE AND UNSATURATED PYRROLIDINONE BASED DONOR ACCEPTOR CONJUGATED POLYMERS: SYNTHESIS, STRUCTURE-PROPERTY AND DEVICE STUDIES." UKnowledge, 2013. http://uknowledge.uky.edu/chemistry_etds/23.
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FLUORINATED ARENE, IMIDE AND LACTAM-FUNCTIONALIZED DONOR ACCEPTOR CONJUGATED POLYMERS: SYNTHESIS, STRUCTURE-PROPERTY AND DEVICE STUDIES
After the discovery of doped polyacetylene, organic semiconductor materials are widely studied as high impending active components in consumer electronics. They have received substantial consideration due to their potential for structural tailoring, low cost, large area and mechanically flexible alternatives to common inorganic semiconductors. To acquire maximum use of these materials, it is essential to get a strong idea about their chemical and physical nature. Material chemist has an enormous role to play in this novel area, including development of efficient synthetic methodologies and control the molecular self-assembly and (opto)-electronic properties. The body of this thesis mainly focuses on the substituent effects: how different substituent’s affect the (opto)-electronic properties of the donor-acceptor (D-A) conjugated polymers. The main priority goes to understand, how different alkyl substituent effect to the polymer solubility, crystallinity, thermal properties (eg: glass transition temperature) and morphological order. Three classes of D-A systems were extensively studied in this work. The second chapter mainly focuses on the synthesis and structure-property study of fluorinated arene (TFB) base polymers. Here we used commercially available 1,4-dibromo-2,3,5,6-tetrafluorobenzene (TFB) as the acceptor material and prepare several polymers using 3,3’-dialkyl(3,3’-R2T2) or 3,3’-dialkoxy bithiophene (3,3’-RO2T2) units as electron donors. A detail study was done using 3,3’-bithiophene donor units incorporating branched alkoxy-functionalities by systematic variation of branching position and chain length. The study allowed disentangling the branching effects on (i) aggregation tendency, intermolecular arrangement, (iii) solid state optical energy gaps, and (iv) electronic properties in an overall consistent picture, which might guide future polymer synthesis towards optimized materials for opto-electronic applications. The third chapter mainly focused on the structure-property study of imide functionalized D-A polymers. Here we used thiophene-imide (TPD) as the acceptor moiety and prepare several D-A polymers by varying the donor units. When selecting the donor units, more priority goes to the fused ring systems. One main reason to use imide functionality is due to the, open position of the imide nitrogen, which provides an attaching position to alkyl substituent. Through this we can easily manipulate solubility and solid state packing arrangement. Also these imide acceptors have low-lying LUMOs due to their electron deficient nature and this will allow tuning the optical energy gap by careful choice of donor materials with different electron donating ability. The fourth chapter mainly contribute to the synthesis and structure property study of a completely novel electron acceptor moiety consist of a unsaturated pyrrolidinone unit known as Pechmann dye (PD) core. Pechmann dyes are closely related to the Indigo family. This can refer as 3-butenolide dimer connected via an alkene bridge, containing a benzene ring at the 5 and 5’ positions of the lactone rings. We have prepared several D-A polymers using this PD system with benzodithiophene (BDT) as the donor unit. Different to common D-A polymers the HOMO and LUMO of the PD acceptor moiety are energetically located within the gap of the BDT, so that the electronic and optical properties (HOMO-LUMO transition) are dictated by the PD properties. The promising electronic properties, band gaps, high absorption coefficients and broad absorption suggest this new D-A polymers as an interesting donor material for organic solar cell (OSC) applications.
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Shivhare, Rishi Ramdas [Verfasser], Stefan C. B. [Gutachter] Mannsfeld, and Natalie [Gutachter] Banerji. "Investigation of Low Optical-Gap Donor and Acceptor Materials for Organic Solar Cells / Rishi Ramdas Shivhare ; Gutachter: Stefan C. B. Mannsfeld, Natalie Banerji." Dresden : Technische Universität Dresden, 2020. http://d-nb.info/1227315708/34.
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Ponsot, Amanda Eileen. "SYNTHESIS OF TETRABENZO[18]CYCLYNE CROSS-CONJUGATED MACROCYCLES WITH FOCUS ON THE DONOR-ACCEPTOR INDUCED FUNCTIONALITY." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1280887889.
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Seger, Mark J. "OPTIMIZATION OF THE OPTICAL AND ELECTROCHEMICAL PROPERTIES OF DONOR-ACCEPTOR COPOLYMERS THROUGH FUNCTIONAL GROUP AND SIDE CHAIN MODIFICATION." UKnowledge, 2013. http://uknowledge.uky.edu/chemistry_etds/25.
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Donor-acceptor copolymers have received a great deal of attention for application as organic semiconductors, in particular as the active layers in low-cost consumer electronics. The functional groups grafted to the polymer backbones generally dictate the molecular orbital energies of the final materials as well as aid in self-assembly. Additionally, the side chains attached to these functional groups not only dictate the solubility of the final materials, but also their morphological characteristics. The bulk of the research presented in this dissertation focuses on the synthesis and structure-property relationships of polymers containing novel acceptor motifs. Chapter 2 focuses on the synthesis of 1,2-disubstituted cyanoarene monomers as the acceptor motif for copolymerization with known donors. It was found that cyanation of both benzene and thiophene aromatic cores resulted in a decrease of the molecular orbital energy levels. Additionally, the small size of this functional group allowed favorable self-assembly and close π-stacking to occur relative to related acceptor cores carrying alkyl side chains as evidenced by UV-Vis and WAXD data. Chapter 3 describes the systematic variation of side chain branching length and position within a series of phthalimide-based polymers. Branching of the side chains on bithiophene donor units resulted in the expected increase in solubility for these materials. Furthermore, a correlation was found between the branching position, size, and the HOMO energy levels for the polymers. Additionally, it was demonstrated that branching the alkyl side chains in close proximity to polymer backbones does not disrupt conjugation in these systems. A novel acceptor motif based on the 1,3-indanedione unit is presented in Chapter 4. Despite the stronger electron withdrawing capability of this functional group relativeto phthalimide, it was found that polymers based on this unit have the same HOMO molecular orbital energy levels as those presented in Chapter 3. It was found, however, the presence of orthogonal side chains greatly enhanced the solubility of the final polymers. Additionally, UV-Vis and WAXD measurements revealed that thermal annealing had a profound effect on the ordering of these polymers. Despite the presence of orthogonal side chains, long range order and close π-stacking distances were still achieved with these materials. Finally, alkynyl “spacers” were used in Chapter 5 to separate the solubilizing alkyl side chains from the polymer backbones on bithiophene donor monomers. The alkynyl groups allowed for conjugated polymer backbones to be achieved as well as low HOMO energy levels. A correlation between the side chain size, π-stacking distances and HOMO-LUMO energy levels was measured in this polymer series.
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Flynn, John J. "Optimizing the Discovery and Processability of Biologically Derived Molecular Glass Host Materials for Photonic Applications." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1588192751503223.
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Delices, Annette. "Organized Organic Dye / Hole Transporting Materials for TiO2- and ZnO- based Solid-State Dye-Sensitized Solar Cells (s-DSSCs)." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC066/document.
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En raison des problèmes d'instabilité à moyen termes des cellules solaires à colorant (DSSC), l'électrolyte liquide à base d'iodure a été remplacé par plusieurs types de matériaux solides transport de trous (HTM) pour obtenir des DSSCs à l'état solide (s-DSSCs). Parmi ces matériaux, l’utilisation des polymères conducteurs(PC) a attiré une attention considérable en raison de leur bonne stabilité, de leur haute conductivité et de la facilité de leur dépôt sur le semi-conducteur mésoporeux TiO2. Dans ce travail de thèse, plusieurs s-DSSCs basées sur des PC utilisés comme HTM ont été développés dans le but d'améliorer leurs performances photovoltaïques en tenant compte des deux objectifs suivants: (i) l'optimisation des processus de transfert inter facial de charge dans la cellule solaire, et (ii) l'optimisation du transport de charge dans le semi-conducteur d'oxyde de type n. Pour atteindre ces objectifs, chaque composant de la s-DSSC a été modifié afin d'étudier son effet sur les performances du dispositif final. En première tentative, une étude analytique est réalisée en faisant varier le sensibilisateur afin de déterminer les fragments de la structure du colorant, qui ont un effet important sur le processus de photopolymérization électrochimique in-situ (PEP) à la fois en milieu organique et en milieu aqueux mais aussi sur les performances des s-DSSCs. Sur la base de ces résultats, un nouveau concept a été développé et consiste en la suppression totale de l'interface entre le colorant et le HTM. Ceci est obtenu par la synthèse de nouveaux colorants liés de façon covalente à un monomère électroactif qui est co-polymérisé par la PEP in-situ. Le copolymère résultant, utilisé comme HTM, est lié de manière covalente au colorant. En outre, la nature de la liaison chimique, reliant le résidu triphénylamine TPA au monomère, est également étudiée comme un facteur clé dans les performances de s-DSSC. En outre, et pour optimiser les processus de transport de charges dans ce type de s-DSSC, de nouvelles s-DSSC basées sur ZnO ont été réalisées et étudiéesDue to instability problems of dye sensitized solar cells (DSSCs) in longtime uses, the iodine based liquidelectrolyte has been replaced by several types of solid hole transporting materials (HTM) to perform solidstate DSSCs (s-DSSCs). Among them, the substitution by conducting polymers (CP) has attractedconsiderable attention because of their good stability, high hole-conductivity and simple deposition withinthe mesoporous TiO2 semiconductor. In this thesis work, several s-DSSCs based on CPs used as HTM havebeen developed in order to improve their photovoltaic performances taking into account the following twoobjectives: (i) the optimization of the interfacial charge transfer processes within the solar cell, and (ii) theoptimization of the charge transport within the n-type oxide semiconductor. To reach these goals, eachcomponent that constitutes the device was varied in order to investigate its effect on the device’sperformances. As first attempt, an analytical study is carried out by varying the sensitizer in order todetermine the fragments of the dyes structures, that have an important effect on the in-situ photoelectrochemical polymerization process (PEP) both in organic and in aqueous media and hence on theperformances of the s-DSSCs. Based on these results, a new concept of removing completely the interfacebetween the dye and the HTM is developed. This is achieved by the synthesis of new dyes covalently linkedto an electroactive monomer which is co-polymerized by in-situ PEP. The resulting co-polymer, used asHTM, is covalently linked to the dye. In addition, the nature of the chemical bond linking the triphenylamineresidue TPA to the monomer is also investigated as a key factor in the s-DSSCs performances. Besides, andto optimize the charge transport processes within this type of s-DSSC, the elaboration of novel ZnO baseds-DSSCs has been achieved and investigated
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Zhang, Bei. "STUDY OF THE EFFECT OF STERIC BULK OF SIDE CHAINS ON THE PROPERTIES OF CONJUGATED POLYMERS." UKnowledge, 2018. https://uknowledge.uky.edu/chemistry_etds/95.
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Donor-acceptor conjugated polymers opened a new era for conjugated polymer research due to the abundant selection and combination of different conjugated units. This class of polymers function as semiconductor materials with potential application in plastic consumer electronics. The frontier molecular orbital energies of the polymers are generally determined by the selection of donor and acceptor units in the backbone structure, and their substituents. The side chains attached to the backbone not only affect the solubility of the materials, but also their self-assembly and morphological characteristics, which indirectly govern optoelectronic properties. It is important therefore to consider backbone architectures and the side chains together, to control (opto)-electronic properties for specific applications, while also maintaining solution processability without disrupting solid-state packing.
The research presented in this dissertation focuses largely on the side chains: how the bulk and position of side chains affect the (opto)-electronic properties of select donor-acceptor (D-A) conjugated polymers. More precisely the intent is to vary the size and position of branches in the alkyl side chains of donor-acceptor polymers, in the attempt to solubilize poorly soluble polymers, without disrupting self-assembly of the polymer backbones into close p-stacks. After an introductory chapter 1, chapter 2 mainly focuses on the synthesis and structure-property study of polymers with 2,3,5,6-tetrafluorobenzene (TFB) as the acceptor motif and benzo[1,2-b:4,5-b′]dithiophene (BDT) as donor units carrying solubilizing substituents. TFB units were chosen based on previous observations that this acceptor unit imparts particularly poor solubility to various donor-acceptor copolymers. The current study indicates that bulky branches placed close to the polymer backbone could solubilize the PBDTTFB copolymers without altering the absorption profile and oxidation potentials. Optical, wide-angle x-ray diffraction (WAXD) and solubility studies shows that solubility is closely related to branching size and position. As the branch size in increased, the solubility of these polymers undergoes a step-change.
The third chapter mainly focuses on the structure-property study of D-A polymers with thienopyrroledione (TPD) as acceptor. Unlike TFB, this acceptor can carry additional side chains that can compete with the space-filling demands of the donor unit side chains. As donor, the rigid BDT unit was compared with 3,3’-dialkoxy-2,2’bithiophene (RO2T2) units which have a similar size, but contain a “swiveling” central σ-bond. Bulkiness of side chains attached to the T2 units should be expected to have a more severe impact, possibly causing the two thiophene units of the T2 units to twist out of plane. It was demonstrated that alkoxy side chains with bulky branches in close proximity to the polymer backbones does not disrupt conjugation in these polymers. The UV-Vis absorption spectra of RO2T2-TPD polymers were red-shifted (more than 120 nm) in comparison to PBDTTPD polymers due to the smaller Eg (energy gap), which might be attributed to the expected higher energy HOMO imparted by the donor unit. The π-π stacking of polymers with BDT units was little affected by the bulky side chains. However, the π-π stacking of polymers with RO2T2 units was much more sensitive to side-chain bulk, with high degree of order and close π-π stacking only if proper local free spacing exists for side-chain interdigitation.
Chapter 4 reports efforts to study polymers from the same set of RO2T2 monomers studied in Chapter 3, but without acceptor units that might otherwise drive self-assembly. RO2T2 homopolymers were synthesized via the Grignard metathesis (GRIM) method. Further, copolymers were prepared with RO2T2 units alternating with thiophene, thieno[3,2-b]thiophene or bithiophene. The spectroscopic studies suggest these polymers with bulky side chains exhibit some varying level of backbone conjugation. Somewhat surprisingly, despite an expected decrease in the strength of intermolecular donor-acceptor interactions, the solubilities were in some cases low, but varied with volume fraction of side chains. Further, even for polymers that appear to easily dissolve, aggregation in solution is so extensive as to give ensembles “too large” for characterization by GPC and or solution NMR. Oxidation potentials seem essentially insensitive to any of the structural variables (governed mostly by the backbone RO2T2 units).
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Fuchs, Franz. "Systèmes modèles donneur accepteur pour le photovoltaïque organique étudiés par microscopie à sonde locale." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY036/document.
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Pour cette thèse, des systèmes donneur-accepteur (DA) modèles pour le photovoltaïque organique ont été étudiés par microscopie à force atomique en mode non contact (nc-AFM) et microscopie à sonde de Kelvin (KPFM). Ces systèmes DA présentent une structure et des propriétés électroniques mieux contrôlées que dans la plupart des hétérojonctions DA en volume.Afin, d'étudier les propriétés optoélectroniques d'architectures DA présentant une séparation de phase à l'échelle de la dizaine de nanomètres, il est indispensable d'optimiser la résolution des modes nc-AFM/KPFM. Dans ce travail, l'influence du régime d'interaction pointe-surface sur les mesures a été étudiée dans le cas d'auto-assemblages de P3DDT sur substrat HOPG. Nous avons ainsi démontré que l'imagerie dans le régime d'interaction à courte portée améliore non seulement la résolution latérale, mais permet également de réaliser des mesures de hauteur plus réalistes.Ensuite, un système DA à base de FG1:[70]PCBM a été étudié. Pour ce mélange DA, la nanostructure et l'échelle de la séparation de phase peuvent être ajustées grâce aux propriétés cristal liquide du composé donneur FG1. Les potentiels mesurés dans le noir sont consistants avec la morphologie attendue en surface et en volume. La relation entre le photo-potentiel de surface (SPV) et le régime d'interaction pointe-surface a pu être précisément analysée. Une résolution optimale est obtenue dans les images de SPV en travaillant près du seuil de dissipation.Enfin, une nouvelle génération de diades comprenant des groupements donneur et accepteur a été étudiée. La nature de l'auto-assemblage sur HOPG a été établie sur la base d'études comparatives de microscopie à effet tunnel et de nc-AFM, avec le support de simulations en mécanique et dynamique moléculaire. Les mesures de photo-potentiel de surface ont ensuite permis de démontrer qu'il était possible d'étudier les mécanismes de photo-génération des porteurs jusqu'à l'échelle de la mono-couche moléculaireDuring this thesis, model donor-acceptor (DA) systems for organic photovoltaics have been studied by non-contact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM). To enhance the understanding of the optoelectronic processes on the nanoscale, DA systems with better defined structural and electronic properties than the one of most bulk heterojunction blends (BHJ), have been studied.With DA phase-separations of below 10nm in organic photovoltaic systems, the highest possible resolution has to be achieved by KPFM to investigate optoelectronic processes. It has been shown that nc-AFM/KPFM measurements in the regime of short range (SR) forces can increase imaging resolution. In preparation of such investigations, the influence of the interaction regime on the topographic measurement via KPFM has been studied for a self-assembly of P3DDT on HOPG. It is demonstrated that imaging in the SR-regime not only increases the lateral resolution, but also assures a correct topographic height values.In a next step, DA blends of FG1:[70]PCMB have been studied by KPFM. For these BHJs, the structure and the scale of the DA phase-separation can be tuned via the liquid crystal behavior of the donor FG1. The in dark potential contrasts are consistent with surface and bulk morphology. The relationship between the surface photovoltage (SPV) and the tip-sample interaction regime has been analyzed. An optimal resolution for SPV imaging is obtained when measuring next to the onset of dissipation.Finally, a new generation of DA dyad with donor and acceptor moieties has been studied. Its self-assembly on HOPG has been determined via a comparative study by scanning tunneling microscopy and nc-AFM plus molecular mechanics and dynamics simulations. By KPFM the charge carrier generation and collection has been analyzed down to the level of a single molecular layer. A clear relationship between the dyads' molecular assembly and their photovoltaic properties can be established
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Zeudmi, Sahraoui Djamila. "Étude computationnelle des propriétés structurales des matériaux BaMxZr1-xO3 (M=Y, In et Sc ; x=0,125, 0,25 et 0,375) en relation avec leur conductivité protonique." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2012. http://www.theses.fr/2012ENCM0022.
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À l'heure actuelle, le développement dans les piles à combustible gagne un regard considérable pour la cogénération de l'énergie propre. Plus particulièrement, les piles à combustible à conduction protonique dont leurs électrolytes sont des oxydes de type pérovskite. Nous nous sommes intéressés aux électrolytes des piles de type PCFC « Proton Ceramic Fuel Cell » dont la température de fonctionnement est intermédiaire. L'intérêt porté pour l'amélioration de la diffusion du proton au sein de ces matériaux implique une compréhension fondamentale de l'interaction du proton avec son environnement. Cette problématique a conduit à une étude systématique en appliquant l'approche de la théorie de la fonctionnelle de la densité sur les matériaux de BaMxZr1-xO3 (M=Y, In et Sc ; x=12,5, 25 et 37,5%). Dans un premier temps, la validation de la méthode appliquée sur le système idéal de BaZrO3 et BaZr0,625Y0,375O3 a été nécessaire afin de reproduire les propriétés électroniques, structurales et de vibration de phonon en bon accord avec les résultats expérimentaux. Dans un deuxième temps, la variation des propriétés électroniques et structurales en fonction de la nature du dopant accepteur (M=Y, In et Sc), sa répartition dans le réseau, et sa concentration ont été étudiées. Une distorsion locale autour de l'atome dopant dans le réseau a été obtenue. Par conséquent, une baisse de symétrie du réseau a été déterminée. Cette distorsion est remarquée quel que soit la nature du dopant. La différence la plus marquée de l'effet de la nature du dopant est trouvée sur les charges atomiques des ions oxygène selon trois environnement possible : Zr-O(1)-Zr, Zr-O(2)-M et M-O(3)-M. Une diminution de la charge (et donc diminution de la basicité) sur le site O3 est bien remarquée dans BaMxZr1-xO3. On attribue cette diminution de charge à la formation d'une liaison covalente à caractère anti-liant Y-O2 (O3). La liaison est ionique pour Sc-O2(O3) et covalente de faible caractère liant pour In-O2 (O3). Nous avons poursuivi nos investigations sur l'insertion d'hydrogène dans les matériaux étudiés. L'analyse des propriétés électroniques, structurales, des vibrations de phonon et l'énergie d'interaction de l'hydrogène des structures BaMxZr1-xO3H, nous ont permis d'établir une corrélation entre le caractère de la liaison chimique M-O, l'insertion du proton et la force de la liaison O-H. L'insertion de H sur le site O3 dans BaYxZr1-xO3 (x=0,25 et 0,375) n'est pas obtenue, probablement à cause de la faible basicité de l'ion oxygène dans la configuration Y-O3-Y. L'insertion du H sur le site O3 pour les deux configurations In-O-In et Sc-O-Sc est obtenue dans BaInxZr1-xO3 (x=0,25 et 0,375) et BaScxZr1-xO3 (x=0,25 et 0,375) respectivement. La variation de l'énergie d'interaction de l'hydrogène avec son environnement dévoile une stabilisation des défauts protoniques significativement plus importante dans le cas de l'atome dopant accepteur yttrium que dans le cas des dopants In et Sc. L'analyse des fréquences de vibration de valence de la liaison O-H a montrée que cette liaison est plus forte dans BaInxZr1-xO3 et BaScxZr1-xO3 que dans BaYxZr1-xO3. En conclusion, nos résultats démontrent que le matériau BaZrO3 dopé en Y favorise plus la formation des défauts protoniques avec une liaison O-H moins forte que dans les matériaux baryum zirconates dopés en In et ScAt the present, the development of fuel cells gains a significant interest for their application in clean energy technologies, more specifically, the proton conducting fuel cells. We are interested in the perovskite oxides electrolytes used in PCFC fuel cell “Proton Ceramic Fuel Cell” which operates at intermediate temperature. The interest for the improvement of proton diffusion in these materials necessitates a fundamental systematic understanding of the proton interaction with its environment. Therefore we applied Density Functional Theory based approach on ideal BaZrO3 and doped barium zirconates BaMxZr1-xO3 (M=Y, Sc and In ; x=12.5, 25 and 37.5%), currently known among the best candidates for PCFC electrolytes. First, the validation of the method applied to the ideal system and BaY0.375Zr0.625O3 was necessary in order to reproduce the electronic, structural and phonon vibration in good agreement with the experimental results. Second, the variation of electronic and structural properties and of the phonon vibration was studied as a function of acceptor dopant nature, positions in the lattice and concentration. A local distortion around the dopant atom in the lattice was obtained. Therefore a reduction of the symmetry system has been determined. This distortion is noticeable regardless of the nature of the dopant. The most striking difference due to the dopant nature is found for the atomic charges on three possible oxygen environments : Zr-O(1)-Zr, Zr-O(2)-M and M-O(3)-M. A decrease in the atomic charge of O3 site (decrease of basicity) is well observed in BaYxZr1-xO3. This decrease in the charge can be attributed to the formation of a covalent anti-binding Y-O2(O3) bond. The binding is ionic for Sc-O2 and slightly covalent with a maximum of 15% covalency for In-O2. Our next investigations were focused on the insertion of hydrogen in the studied materials. The analysis of the computed electronic and structural properties, phonon vibrations and hydrogen interaction energies allowed us to establish a correlation between the nature of the chemical bonding M-O, the insertion energy of the proton and the O-H bond strength. The insertion of hydrogen in O3 site in BaYxZr1-xO3 (x=0.25 and 0.375) is not obtained, probably due to the low basicity of the oxygen ion in the configuration Y-O-Y. The insertion of H at the oxygen site for both In-O3-In and Sc-O3-Sc configurations found to be energetically favored in BaInxZr1-xO3 (x=0.25 and 0.375) and BaScxZr1-xO3 (x=0.25 and 0.375) respectively. The variation of hydrogen interaction energy with its environment reveals a significantly stronger stabilization of proton defects in the case of yttrium acceptor dopant than in the two other barium zirconates doped with In and Sc. The analysis of O-H stretching vibration frequencies has shown that the O-H bond is stronger in BaInxZr1-xO3 and BaScxZr1-xO3 than in BaYxZr1-xO3. In conclusion, our results show that the Y doped barium zirconate material favors the formation of proton defects, with a weaker O-H bond than in In and Sc doped oxides
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Rodriguez-Santiago, Alan J. "Synthesis and Characterization of Fe8-based Materials as Electron Acceptors for Solar Energy Applications." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3805.
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The urgent need to find alternative sources of energy has been recognized as a major challenge of the 21st century. Many ideas have been proposed, but harvesting the energy of the Sun has been identified by many as the most promising alternative to satisfy the world’s increasing energy demand. Among the current technologies to harness solar energy, photovoltaics and artificial photosynthesis (photocatalysis) stand out. Although very different in their strategies, both technologies entail a core principle, the generation of a charge-separated state. To this end, both methods employ electron acceptors that will receive the photo-electron; in most cases this role is played by C60 or its derivatives. Our research group has synthesized and characterized an octanuclear iron-oxo cluster with remarkable electrochemical properties which compares favorably with the reduction potentials of C60 and derivatives. This dissertation explores the use of this octanuclear cluster as electron acceptor for solar energy applications.
To assess the viability of Fe8 as an electron acceptor in photocatalysis, electron donors that could coordinate to its iron atoms via phenol groups were synthesized and characterized. These electron donors were used in efforts to make molecular dyads, but coordination was not achieved. The altenative strategy studied was the preparation of Fe8-based hybrid materials that can be casted with known polymer electron donors. Several hybrid materials were prepared and their general properties investigated. These materials exhibited the desired electrochemical traits as well as the general castable behavior of the polymer host. These hybrids are now ready to be tested in polymer solar cells.
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Grelaud, Guillaume. "New electrochromic organometallic materials for light modulation." Phd thesis, Rennes 1, 2012. http://www.theses.fr/2012REN1S120.
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Au cours de cette thèse, de nouveaux complexes alcynyles du fer et du ruthénium ont été synthétisés et caractérisés. Ces composés ont été élaborés pour permettre l'électro-commutation de leurs propriétés en optique non linéaire (ONL) entre plusieurs états redox. Dans un premier temps, des unités hétéro-bimétalliques ferrocène-ruthénium ont été étudiées. Il a pu être démontré que ces unités, qui sont des complexes à valence mixte de classe II dans leur état mono-cationique, possèdent les propriétés électrochromiques requises pour leur incorporation dans des assemblages conjugués plus étendus et actifs en ONL. Dans un second temps, des complexes octupolaires possédant un espaceur central de type triphénylamine ou oxyde de triphénylphosphine ont été préparés. Dans le cas des premiers, un complexe octupolaire hexanucléaire à six états redox distincts a été obtenu tandis qu'avec les seconds, un espaceur plus ‟étendu” a été requis pour optimiser les propriétés optiques de ces assemblages. Un électrochromisme marqué a pu être observé en solution pour tous ces complexes. Finalement, d'autres assemblages organométalliques ont également été étudiés. Ainsi, la fonctionnalisation d'un groupement ferrocényl-alcynyl de ruthénium avec un alcyne vrai a permis de greffer cet ensemble dinucléaire original sur une surface de silicium, ouvrant la voie à l'obtention d'interfaces électro-commutables. Par ailleurs, le potentiel des complexes ferrocényl-allénylidènes du ruthénium pour moduler les propriétés optiques de ce chromophore à la fois par oxydation et par réduction a été mis en évidenceDuring this PhD, new iron and ruthenium alkynyl complexes have been synthesized and characterized. These complexes had been prepared in order to switch their nonlinear optical properties between their different redox states using an electrochemical process. Firstly, ferrocenyl ruthenium alkynyl units have been studied. It has been shown that these heterobimetallic units, which are class-II mixed-valent complexes in their mono-cationic state, possess all the required electrochromic properties for their incorporation into more extended and conjugated NLO active assemblies. Then, triphenylamine- and triphenylphosphine oxide-cored octupolar complexes had been prepared. In the first case, a hexanuclear complex with six distinct redox state had been obtained whereas in the second, an ‟extended” triphenylphosphine oxide core had been developed in order to optimize their optical properties. In both cases, a marked electrochromic behavior in solution of the complexes has been observed. Finally, other organometallic dinuclear assemblies have been explored. Thus, functionalization of the ferrocenyl ruthenium alkynyl synthons with a terminal alkynyl bond has allowed the grafting of this complex onto a silicon surface, paving the way for electroswitchable materials. Alternatively, the potential of ferrocenyl ruthenium allenylidene complexes to modulate the (nonlinear) optical properties using both oxidative and reductive processes has been demonstrated
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Browning, Charles. "Diimine(dithiolate)platinum(ii) Chromophores: Synthesis, Spectroscopy, and Material Applications." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc699877/.
Full textAbstract:
A series of 28 square-planar dithiol(diimine)platinum(II) chromophoric complexes have been synthesized, characterized, and evaluated for potential efficacy in sensitization of solid state photovoltaic devices to the near-infrared regions of the electromagnetic spectrum. The effect of molecular stacking in the solid state and self-association in solution are shown to influence spectral, electronic, and magnetic properties of the chromophores. Such properties are investigated in the pure form and as partners in donor-acceptor charge transfer adducts. Finally, selected chromophores have been incorporated into single layer schottky diodes as neat films and as dopants in multi-layer organic photovoltaic devices. Evaluation of the devices internal quantum efficiency and voltage-current was measured as proof of concept.
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Gohlke, David Christopher. "Tuning the Properties and Interactions of Manganese Acceptors in Gallium Arsenide with STM." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354669837.
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Ebenhoch, Bernd. "Organic solar cells : novel materials, charge transport and plasmonic studies." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/7814.
Full textAbstract:
Organic solar cells have great potential for cost-effective and large area electricity production, but their applicability is limited by the relatively low efficiency. In this dissertation I report investigations of novel materials and the underlying principles of organic solar cells, carried out at the University of St Andrews between 2011 and 2015. Key results of this investigation: • The charge carrier mobility of organic semiconductors in the active layer of polymer solar cells has a rather small influence on the power conversion efficiency. Cooling solar cells of the polymer:fullerene blend PTB7:PC₇₁BM from room temperature to 77 K decreased the hole mobility by a factor of thousand but the device efficiency only halved. • Subphthalocyanine molecules, which are commonly used as electron donor materials in vacuum-deposited active layers of organic solar cells, can, by a slight structural modification, also be used as efficient electron acceptor materials in solution-deposited active layers. Additionally these acceptors offer, compared to standard fullerene acceptors,advantages of a stronger light absorption at the peak of the solar spectrum. • A low band-gap polymer donor material requires a careful selection of the acceptor material in order to achieve efficient charge separation and a maximum open circuit voltage. • Metal structures in nanometer-size can efficiently enhance the electric field and light absorption in organic semiconductors by plasmonic resonance. The fluorescence of a P3HT polymer film above silver nanowires, separated by PEDOT:PSS, increased by factor of two. This could be clearly assigned to an enhanced absorption as the radiative transition of P3HT was identical beside the nanowires. • The use of a processing additive in the casting solution for the active layer of organic solar cells of PTB7:PC₇₁BM strongly influences the morphology, which leads not only to an optimum of charge separation but also to optimal charge collection.
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Fernando, Juwanmandadige Roshan. "Tuning the Opto-Electronic Properties of Core-Substituted Naphthalenediimides through Imide Substitution." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1401984667.
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Andersson, Maria, and Madeleine Sellin. "Frikoppling eller samordning? : En studie om avskaffandet av sambandet mellan redovisning och beskattning för K2 företag." Thesis, Karlstad University, Faculty of Economic Sciences, Communication and IT, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-4519.
Full textAbstract:
Syftet med denna uppsats är att få en djupare insikt om hur en frikoppling mellan redovisning och beskattning skulle kunna se ut. Genom att undersöka hur revisionsbolagen ställer sig till SamRoBs förslag om en frikoppling, SOU 2008:80, och vilka konsekvenser ett avskaffande av det materiella sambandet kan medföra för K2-företagen vill vi skapa en djupare förståelse i diskussionen om en total frikoppling av det materiella sambandet för K2-företagen.
Uppsatsens undersökning utgår från en kvalitativ forskningsmetod och har en analytisk ansats. Data består av primär- och sekundärdata som kritiskt granskas för att bedöma undersökningens giltighet och tillförlitlighet.
För att skapa förståelse kring sambandet mellan redovisning och beskattning presenteras relevanta begrepp och teorier. Vidare redogörs för innehållet i utredningen SOU 2008:80.
Empirin presenterar respondenternas åsikter och synpunkter om utredningens, SOU 2008:80, förslag om en frikoppling mellan redovisning och beskattning. Respondenterna avser tre anställda från tre av de största revisionsbolagen i Sverige.
För K2 företag innebär en frikoppling i praktiken en samordning. Om SamRoBs förslag anpassas till K2 reglerna kommer det nya regelverket i längden innebära en förenkling för K2 företagen. I stora drag kommer inte revisorernas arbete att förändras även om dagens revisorer kan tycka att arbetsbördan blir tyngre.
The purpose of the thesis is to gain a deeper insight into a decoupling between accounting and taxation. By a study on the audit firms’ attitude concerning SamRoBs proposal on decoupling and what affects K2 companies may be facing are we intending to create a deeper understanding in the discussion of a total decoupling of the material relationship for K2 companies.
The study is based on a qualitative research and has an analytical approach. The data consists of primary and secondary data that is critically reviewed to assess the validity and reliability of the study.
In order to create understanding of the relationship between accounting and taxation relevant concepts and theories are presented. The contents of SOU 2008:80 will also be described.
The empirical data presents the respondents´ views and comments on the proposal, SOU 2008:80, for a decoupling between accounting and taxation. Respondents interviewed were three employees from three of the largest audit firms in Sweden.
The true meaning of decoupling for K2 companies in practice is coordination. If SamRoBs proposal is adapted to the K2 regulation a new framework will appear and in the long run involve a simplification for K2 companies. Broadly, the work of the auditing firms will not mean considerable changes even though current auditors may think the workload will increase.
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Faulmann, Christophe. "Conducteurs derives de metaux de transition : complexes moleculaires, polymeres, oxydes de cuivre." Toulouse 3, 1988. http://www.theses.fr/1988TOU30160.
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Jean, Bruno. "Propriétés électriques, optiques et électro-optiques du semiconducteur CdIn2 Te4." Bordeaux 1, 1994. http://www.theses.fr/1994BOR10553.
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Cette these est consacree aux proprietes electriques, optiques et electro-optiques du semiconducteur ternaire cdin#2te#4. La premiere partie de la these est consacree a l'etude des proprietes optiques et de transport par absorption optique, photoluminescence, photoconductivite et effet hall. La compensation du materiau, due a des defauts antisites dans le sous reseau cationique, a ete mise en evidence par effet hall. Un niveau accepteur situe a environ 40 mev de la bande de valence a ete observe en photoconductivite. D'autre part, l'asymetrie des mesures de conductivite par la methode de van der pauw et aussi des spectres dlts (deep level transient spectroscopy) dont la forme depend de la tension de polarisation ont montre la presence d'un desordre a moyenne distance. Les fluctuations spatiales des bords de bandes qui en resultent permettent d'expliquer la plupart des resultats experimentaux. Enfin, un niveau donneur profond, situe a 0. 5 ev environ sous la bande de conduction, a ete observe par luminescence sur les echantillons presentant un ecart a la stchiometrie important. La seconde partie de ce travail est consacree au reexamen de la mesure du coefficient electro-optique r#4#1 en mode longitudinal. Nous montrons que les classiques mesures en detection synchrone peuvent conduire a des resultats errones si les electrodes transparentes n'ont pas un caractere ohmique. Un modele theorique est ensuite developpe pour rendre compte de la distribution particuliere du champ electrique due au caractere schottky des contacts. Les resultats de diverses mesures en champ electrique continu sont en bon accord avec le modele et nous permettent alors de proposer une nouvelle valeur du coefficient r#4#1, proche de 3pmv##1
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Huang, Jen-Hsien, and 黃任賢. "Donor-acceptor Conjugated Organic Materials for Bulk Heterojunction Solar Cells." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/81936876756252249535.
Full textAbstract:
博士臺灣大學
化學工程學研究所
98
Over the past two decades, satisfying the world’s growing demand for energy is one of the most significant challenges facing society. Therefore, the development of solar energy is viewed as an ideal technology for power generation because it is clean and renewable. Although the photovoltaic (PV) technology platforms of silicon-based PV and thin-film PV are now undergoing a rapid expansion in production, the next generation PV—organic solar cells —could soon be playing a major role with the advantages of ultralow production costs, rugged and lightweight. The main purpose of this thesis is to fabricate PV cells via an all-solution-process and investigate the influences of materials and fabrication parameters on the device performance. In the first part of this thesis (Chapter 3 and 4), we prepared nanofiber shaped hole collection layer with highly porous structure by changing the structure of EDOT monomer. The highly porous hole collection layer prepared from electrochemical deposition can offer a great deal of interface between the hole collection layer and active layer leading to a more balanced charge mobility. The power efficiency of the device fabricated with porous hole collection layer can achieve 3.57% so far. Furthermore, we also enhance the conductivity of the hole collection layer (PEDOT) by treating the PEDOT with some polyalchols. From the results, it revealed that the conformation of PEDOT can be changed from coiled structure to linear structure after the treatment leading to a higher conductivity. The highly conductive PEDOT was also applied to fabricate PV cells and the power efficiency is about 4.30%. In the second part (Chapter 5), a novel solution-processed small molecule (DFTh-TP) for use in electron donor has been incorporated into the organic solar cells based on P3HT and PC[70]BM. The combination of DFTh-TP with P3HT and PC[70]BM allows not only a broad absorption but also tuning the inter energy level leading to a higher JSC and VOC. The best performing devices exhibited a power conversion efficiency of 4.50 %. The efficiency is increased of almost 15 % compared with the one without incorporating DFTh-TP. In the third part (Chapter 6), we performed a comprehensive analysis of the 2D nanoscale morphology related to the exciton lifetime by combining confocal optical microscopy with a fluorescence module. The results revealed that the film prepared through rapidly grown process leads to an extremely homogeneous blend. The homogeneous phase cannot offer a continuous pathway for charge transport leading to a serious recombination. In the case of slowly grown film, although not all of these pathways may have been ideal, due to the presence of some terminated channels, this system still offered several connected pathways, leading to an interdigitated nanostructure that was responsible for efficient charge transport and the superior value of JSC. This approach provides much fundamental information that is unavailable when using conventional microscopy techniques in the future. In the fourth part (Chapter7~9), we have fabricated organic photovoltaic devices with blends of F8T2 and fullerene as an electron donor and electron acceptor, respectively. A significant improvement of the photovoltaic efficiency was found in device by using PC[70]BM as active material with complementary spectra. Moreover, we also study the effects of nanomorphological chnages on polymer PV devices with blends of F8T2 and PC[60]BM. The morphological changes of blended films were observed upon thermal annealing temperature near and above glass transition temperature (130 oC). Such microstructural transformations resulted in modified charge transport pathways and therefore grately influenced the device performance. The highest PCE of 2.14 % with an VOC of 0.99 V and a JSC of 4.24 mA/cm2 was achieved by device annealing at 70 oC for 20 min. In the final part (Chapter 10), we modified the printing method by increasing the affinity of PDMS for organic solvent via non-destructive solvent treatment. This stamping method eliminates the necessity of any plasma treatment and any possible damages on the PDMS surface and would give full control over the chemical composition and film thickness of each layer. The multilayer polymer structure also demonstrated for photovoltaic applications.
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"Utilization of metal oxide cathode interfacial layer on donor/acceptor solar cells." Thesis, 2011. http://library.cuhk.edu.hk/record=b6075454.
Full textAbstract:
Wang, Mingdong.Thesis (Ph.D.)--Chinese University of Hong Kong, 2011.
Includes bibliographical references.
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
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Fang, Yi-Kai, and 方佾凱. "Donor-Acceptor Polymeric Materials: Syntheses, Properties, and Their Memory Device Applications." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/21110716371436983882.
Full textAbstract:
博士國立臺灣大學
高分子科學與工程學研究所
99
Donor-acceptor type polymers have attracted a significant interest for memory device applications due to their tunable electronic properties through molecular design. However, the effects of the different polymer structure on the memory characteristics have not yet been explored. In this thesis, we address the above issues by exploring the following subjects: (1) design and synthesis of new donor-acceptor organic polymers, (2) preparation and characterization of the memory devices, and (3) correlation of the donor-acceptor polymer structure or composition with memory device characteristics. In the first part of this thesis (chapter 2), the synthesis, structures, morphology, optoelectronic and the memory device properties of poly(3-hexylthiophene)-block-poly(vinylphenyl oxadiazole) donor-acceptor rod-coil block copolymers are reported. The novel donor-acceptor rod-coil diblock copolymers of regioregular poly(3-hexylthiophene) (P3HT)-block-poly(2-phenyl-5-(4-vinylphenyl) -1,3,4-oxadiaz-ole) (POXD) were successfully synthesized contain three different the coil lengths of 5, 18 and 25 repeating units by the combination of a modified Grignard metathesis reaction (GRIM) and atom transfer radical polymerization (ATRP). The small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS) demonstrate that the decreased crystallinity of the block copolymers were duo to the increasing POXD block ratio was depress the crystallization of P3HT. The DSC, UV-vis, CV, TEM and AFM are similar to the SWAXS results. Homopolymers and block copolymers were synthesized and used to evaluate the memory applications. Mismatch of the metal work function relative to the low-lying HOMO and high-lying LUMO levels of POXD, and served as an insulator and trapping center. These block copolymers depend on different the coil (POXD) lengths exhibited different characteristics of these memory devices. The P3HT44-b-OXD5 and P3HT33-b-OXD25 memory devices are hole-transport diode and insulator, respectively. The P3HT44-b-OXD18 memory devices exhibited non-volatile with NDR behavior. In the second part of this thesis (chapter 3), a series of non-conjugated random copolymers containing pendent electron-donating 9-(4-vinylhenyl)carbazole (VPK) and electron-withdrawing 2-phenyl-5-(4-vinylphenyl)1,3,4-oxadiazole (OXD) or 2-(4-vinylbiphenyl)-5-(4-phenyl)- 1,3,4-oxadiazole (BOXD) with three different ratio (8/2, 5/5, 2/8) were successfully synthesized by nitroxide-mediated free radical polymerization (NMRP) method. The prepared random copolymers are denoted as P(VPKxOXDy) or P(VPKxBOXDy) with three different electron donor/acceptor (x/y) ratios of 8/2, 5/5, and 2/8. The electrical switching behavior based on the ITO/polymer/Al device configuration could be tuned through the donor/acceptor ratio or acceptor trapping ability. Both experimental and theoretical results indicated that the charge transfer between the pendant donor and acceptor was relatively weak without significant orbital hybridization. In addition, the low-lying HOMO energy level of OXD or BOXD units was employed as charge trapping site. Therefore, distinct electrical current-voltage (I-V) characteristics changed from diode, to volatile memory, and insulator depending on the relative donor/acceptor ratios of 10/0, 8/2, and (5/5, 2/8 and 0/10), respectively. The memory device based on P(VPK8OXD2) or P(VPK8BOXD2) copolymers exhibited volatile static random access memory (SRAM) behavior with an ON/OFF current ratio of approximately 104-105, up to 107 read pulses, and retention time of more than 1 h. The unstable ON state in the device was due to the shallow trapped holes with spontaneously back transferring of charge carriers when the electric field was removed and thus exhibited the volatile nature. The slightly lower HOMO level of OXD moieties than that of BOXD led to P(VPK8OXD2) device storing the charge for a longer period of time. The present study suggested the high performance polymer memory devices could be achieved by changing the donor/acceptor ratio or chemical structure. In the third part of this thesis (chapter 4), we report the synthesis and resistive-type switching memory characteristics based on new random copolymers of P(VTPAxBOXDy) and P(CNVTPAxBOXDy) containing different donor/acceptor ratios (8/2, 5/5, and 2/8) of pendent electron-donating 4-vinyltriphenylamine (VTPA) or 4,4′-dicyano-4″-vinyl-triphenylamine (CNVTPA) and electron-withdrawing 2-(4-vinylbiphenyl)-5-(4-phenyl)-1,3,4-oxadiazole (BOXD). The effects of donor/acceptor ratios and cyano side group on the memory characteristics were explored and compared with preperties of homopolymers, PVTPA, PCNVTPA, and POXD. The distinct electrical current-voltage (I-V) characteristics of the ITO/P(VTPAxBOXDy) /Al device changed from volatile memory to insulator depending on the relative donor/acceptor ratios. The ITO/P(VTPA8BOXD2) or PVTPA/Al device exhibited DRAM and SRAM behavior, respectively, with an ON/OFF current ratio of 107-108. However, no switching phenomena were observed for a higher BOXD ratio. Moreover, the devices could endure 108 cycles under a voltage pulse and show a long retention time for at least 104 s under a constant voltage stress. The low-lying HOMO energy level of BOXD was employed as hole-blocking units as the charge transport were occurred between the neighboring triphenylamine units. The charge trapping/spontaneously back transferring of trapped carriers controlled the switching behavior. On the other hand, all the P(CNVTPAxBOXDy) memory devices exhibited non-volatile nature with NDR behavior due to the preferred interaction of Al atoms with the cyano group. Here, the results demonstrated that the pendent polymers with specific donor-acceptor chromophores could tune the memory switching characteristics for advanced electronic device applications.
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Chi, Liang-Chen, and 紀良臻. "Synthesis, Properties, and Applications of Carbazole and Fluorene Based Donor-Acceptor Materials." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/51593079639043764332.
Full textAbstract:
博士國立臺灣大學
化學研究所
98
This thesis is composed of two major parts. For the first part, we have successfully synthesized a series of bipolar hosts by introducing two electron-withdrawing moieties onto the 3 and 6 positions of N-phenyl carbazole. The introduced electron-withdrawing blocks are dimesityl boron, phenylbenzimidazole, pyridine, and oxadiazole. The new molecules obtained by different structure combinations have led to different film-forming property, comparable electron and hole mobilities, tunable triplet energies and energy levels which govern their various applications as host materials in phosphorescent organic light-emitting devices (PhOLEDs) with good to excellent external quantum efficiencies (EQE). Among those, CMesB can serve as host material for doping with Firpic (ηext = 12 %, ηp = 19 lm/W) and Ir(ppy)2acac (ηext = 16 %, ηp = 34 lm/W) to realize efficient blue and green PhOLEDs, respectively. High performance PhOLEDs have been achieved with COxaPh as host material doping with green emmitters Ir(ppy)2acac (ηext = 18 %, ηp = 76 lm/W) and red emmiter OS2 (ηext = 21 %, ηp = 36 lm/W). CBzIm can dope with NFirpic) to get a blue PhOLED with EQE up to 16 % and ηp = 29 lm/W. Due to its high photoluminescence, CPhBzIm was not only used to fabricate non-doped deep blue-emitting devices with promising performance (ηext = 3 %, CIE = 0.16; 0.05), but also served as host material doped with Ir(pbi)2acac to realize green PhOLED (ηext = 19.2 %, CIE = 0.42; 0.56). Furthermore, we have demonstrated a simple single-doped way to realize two-color based WOLEDs (ηext = 7 %, CIE = 0.31, 0.33) by using the dual roles of CPhBzIm. CNBzIm served as a universal host host material for Firpic (13 %, ηp = 31 lm/W), Ir(ppy)2acac (18 %, ηp = 59 lm/W), OS2 (ηext = 19 %, ηp = 27 lm/W), and WOLEDs (ηext = 16 %, ηp = 37 lm/W). CAymPy and CSymPy have similar physical properties which were applied as host materials gave devices with Ir(ppy)2acac as emitter (CAymPy, ηext = 12 %, ηp = 47 lm/W, CSymPy, ηext = 11 %, ηp = 42 lm/W) and Ir(mpq)2acac as emitter (CAymPy, ηext = 11 %, ηp = 12 lm/W；CSymPy, ηext = 8 %, ηp = 9 lm/W). The second part, we have successfully synthesized a series of novel bipolar molecules with various donors and acceptors which were bridged with a fluorene conjugation. The donors, mainly diaryl amino groups, were introduced onto the C3 and C6 of the fluorenone core employing Hartwig’s palladium-catalyzed C-N bond coupling reaction of 3,6-dibromofluorenone and diarylamines. After then, cyanoacetic acid, dicyano , and diethyl malonate were introduced as the acceptor parts onto the 9-position of the fluorenone by Knoevenagel condensation. Those bipolar materials have shown to have potential applications of organic thin-film solar cell and photodynamic therapy. The photovoltaic bulk heterojunction solar cells with p-type LCC-1 as the dye in combining with C60 as the electron acceptor have been fabricated by thermal evaporation. These devices have reached power conversion efficiencies of ~1 % and IPCE at 498 nm up to 35 % under simulated AM 1.5 solar irradiation at 100 mWcm-2. In addition, compounds 17 was found to exhibit larger two-photon absorption (TPA) cross section value of 1636 GM as measured by the two photon induced fluorescence. More strikingly, the best single-photon singlet oxygen generation quantum yield (＞100 %) as compared to that of the standard tetraphenylporphyrin (H2TPP) was observed, which indicates the highly potential application in photodynamic therapy is possible in the dye can be designed to interact with cells.
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Lee, Wen-Ya, and 李文亞. "Donor-Acceptor Conjugated Organic Materials for Thin-Film Transistors and Solar cells." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/06180415982363777397.
Full textAbstract:
博士國立臺灣大學
化學工程學研究所
97
Optoelectronic properties of donor-Acceptor conjugated organic materials determine the performances of organic electronics. In this thesis, a systematic study on the synthesis, optoelectronic properties and device characterizations of donor-acceptor conjugated organic materials was investigated. The goals of this thesis is to address the following issues: (1) designing and synthesizing new donor-acceptor organic materials, (2) clarifying the relationship of charge transport and chemical structures, and (3) characterizing the performances of organic electronics, e.g. thin film transistors, photovoltaic cells or light-emitting diodes, based on these studied materials. The objectives and the research findings are summarized as follows: 1. Synthesis, optoelectronic properties, and device applications of new fluorene-based donor-acceptor conjugated polymers (chapter 2): four fluorene-based conjugated polymers, including PFTT, PFDDTQ, PFDTBT, and PFDDTTP, with various acceptor structures, quinoxaline (Q), 2,1,3-benzothiadiazole (BT) and thieno[3,4-b]pyrazine (TP) were explored. It was found that the order of the value in the band gap energy was PFDDTTP < PFDTBT < PFDDTQ < PFTT, which was on the opposite trend of emission maximum and their charge carrier mobility due to the strong electron-withdrawing strength of the TP moiety and the coplanar backbone in PFDDTTP, leading to the highest intramolecular charge transfer and the highest hole mobility among all four polymers. Furthermore, PFDDTQ, PFDTBT, and PFDDTTP were used to fabricate in copolymer/[6,6]-phenyl-C61-butyricacid methyl ester (PCBM) bulk-heterojunction photovoltaic cells. The order in the short-circuit current density (JSC) and power-conversion efficiency (PCE) of the photovoltaic cells was PFDTBT > PFDDTQ > PFDDTTP, which contradicted the order in the band gap energy and mobility. However, the JSC and PCE coincided instead with the order in the mobility of the copolymer/PCBM blend, where the mobility was found to increase in PFDTBT and PFDDTQ devices owing to charge transfer with PCBM, but the mobility deceased in PFDDTTP due to inefficient phase separation resulting from the strong intermole-cular interactions between the polymer chains of PFDDTTP. With its high blended mobility and low band gap, PFDTBT achieved a PCE of 1.1 %. 2. The charge transport characteristics and surface morphology of three thiophene-thieno[3,4-b]pyrazine alternating copolymers (PTHTP-C7, PTHTP-C12, and PBTHTP-C7) (chapter 3). Long alkyl side chains promoted PTHTP-C12 to become a fibrillar-like structure on the hexamethyldisilazane (HMDS)-modified surface and resulted in better charge transport properties than those of the other two copolymers. However, a nodule-like morphology on the octyltrichlorosilane (OTS)-modified surface was observed due to the strong interaction between the non-polar alkyl chains of PTHTP-C12 and highly hydrophobic surface. By further annealing at a higher temperature, a densely packed grain morphology on octyltrichlorosilane (OTS) modified SiO2 surface was observed and led to the field effect mobility of 1.1 × 10-2 cm2V-1s-1. The present study suggests that the thiophene based donor-acceptor conjugated polymers could have a high FET mobility through the manipulation of their morphology. 3. Synthesis, characterization of new alternating copolymers of fluorene and 3,9- or 2,8- substituted di(2-ethylhexyl)-indolo[3,2-b]carbazole (chapter 4). poly(fluorene)-alt-3,9-(indolo[3,2-b]carbazole)) (PF-p-In) and poly(fluorene)-alt-2,8-(indolo[3,2-b]carbazole)) (PF-m-In) were synthesized by palladium-catalyzed Suzuki coupling polymerization and characterized for the applications of light-emitting diodes and field effect transistors (FET). The para-linkage, PF-p-In, facilitates π-electron delocalization and thus has a lower optical band gap and a higher emission maximum than those of the meta linkage, PF-m-In. The electroluminescence devices based on PF-p-In and PF-m-In as the emissive layer show a similar maximum luminance but with different emissive colors of green and blue, respectively. The FET hole mobilities of PF-p-In and PF-m-In are 6.73×10-5 and 1.50×10-4 cm2/V.s, respectively, which are significantly higher than that of polyfluorene. The present study demonstrates the electronic and optoelectronic properties of polyfluorene enhanced by incorporating hole transporting indolocarbazole with different linkages. 4. The solution-processing OTFT characterizations of new core-chlorinated Naphthalene diimide (NDI) derivatives with fluorinated alkyl chains (chapter 5). Four core-chlorinated NDI derivatives, including N,N’-bis(heptafluorobutyl) naphthalene diimide (1), N,N’-bis(heptafluorobutyl)-2,6-dichloro-naphthalene diimide (2), N,N’-bis(nonafluoropentyl)-2,3,6,7-tetrachloro-naphthalene diimide (3) and N,N’-bis(nonafluoropentyl)-2,6-dichloro-naphthalene diimide (4), were studied. A high electron average mobility of 0.17 cm-2V-1s-1 and an excellent ambient stability are observed in OTFT devices made from 2 through solution-sheared deposition method. From charge transport anisotropy measurement, a high mobility of 0.5 cm-2V-1s-1 of 2 was achieved from a perpendicular direction of OTFT. The direction of channel length in the device is vertical to the shearing direction. Furthermore, the threshold voltage of 1 increases dramatically upon exposure to the air because the grain boundaries of 1 provide channels for diffusion of oxygen and moisture, which act as electron traps. From XRD measurement result, it is concluded that the solution-sheared method affect the orientation of crystalline thin films and lower the d-spacing distance, as compared with that of the vapor deposition. This study affords the promising n-type high-performance core-chlorinated NDI derivatives for potential organic electronics.
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Shivhare, Rishi Ramdas. "Investigation of Low Optical-Gap Donor and Acceptor Materials for Organic Solar Cells." Doctoral thesis, 2019. https://tud.qucosa.de/id/qucosa%3A38031.
Full textAbstract:
Development of efficient and clean energy sources to meet the ever-increasing de- mand of humankind is one of the greatest challenges of the 21st century. There is a dire need to decarbonise the power sector, and the focus needs to shift to re- newable resources such as wind and solar energy. In this regard, organic solar cells are a promising and novel technology owing to its low carbon footprint, innovative applications, and possible integration into the current infrastructure. Due to its unique advantages, a considerable research effort has been put into its development in the last decades. As a result, the power conversion efficiency (PCE) of the organic photovoltaics has steadily risen from as low as 0.5% to around 17 % at the current stage. This improvement primarily originates from the better understanding of the underlying physical processes and as a result of extensive material development.
In the most general case, organic solar cells consist of a binary blend of an electron donating and an electron accepting organic semiconductor forming the so-called ‘bulk-heterojunction’ (BHJ) morphology. Thermodynamics places an upper limit on the power conversion efficiency (PCE) of binary blend BHJ devices and for further enhancement in efficiency novel device concepts like the use of ternary blends and tandem device architectures is being investigated. In relation to these approaches, the development of low optical-gap (Eopt ≤ 1.5 eV) organic semiconductors has gained importance as these materials provide for the complementary absorption with respect to the other components and better harvesting of the solar spectrum.
This work mainly deals with the investigation of low optical gap donor and acceptor materials for organic solar cells. We investigate the effect of the molecular structure on the device performance and the photophysical processes in the binary and ternary blend configuration. In the first part of the thesis, we study a family of low optical- gap diketopyrrolopyrrole (DPP) based polymers while varying the conjugated core and the branching position and length of the solubilizing alkyl side chains. The branching position of the side chains is found to have a significant influence on the polymers ability to crystallize, which in turn influences the mobility of free charge carriers. The branching position also affects the solubility of the polymer, which in turn influences the morphology of the bulk-heterojunction (BHJ) and ultimately the yield of photogenerated charge carriers.
To investigate the electron transfer and charge separation dynamics in the blends consisting of DPP polymers and fullerene, we employed ultrafast pump-probe spec- troscopic techniques. In the spectroscopy data, we observe signatures suggesting an ultrafast electron transfer process and an efficient charge separation process due to the high mobility of the free charge carriers shortly after separation (∼10-100 ps).
Lastly, we investigated indacenodithiophene (IDT) based non-fullerene acceptor (NFA) molecules. In particular, we studied the effect of fluorination on the device performance when these acceptors are blended with PTB7-Th and P3HT donor polymers. The kinetics of the photophysical processes in the binary and ternary blends are characterized using ultrafast spectroscopy and related to the morphology of the blend and the molecular structure of the acceptors.
Overall, we investigated the structural variations in the DPP polymers and flu- orinated non-fullerene acceptor (NFA) molecules and suggest design rules for the synthesis of optimal DPP polymers and non-fullerene acceptors to achieve supe- rior device performance. Additionally, we also shed light on the phenomenological processes happening on an ultrafast time scale (0.2-1000 ps) in the binary and the ternary blends with the aim of developing a better understanding of the photophys- ical processes in these promising material systems.
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Reckers, Philip. "Electronic properties of titania (and AZO) and its interface to organic acceptor materials." Phd thesis, 2019. https://tuprints.ulb.tu-darmstadt.de/8559/1/Dissertation_Philip_Reckers_final_Korrektur_ohne_Lebenslauf.pdf.
Full textAbstract:
The focus of this work is on the investigation of the electronic structure at interfaces of inverted organic solar cells and energetic states in the band gap of the anatase (101) surface.
Inverted organic solar cells are a promising alternative to conventional inorganic solar cells, regarding the potentially low production costs and its variety in possible applications. Inverted organic solar cells sometimes exhibit S-shaped I-V characteristics instead of diode-like I-V characteristics, which results in a decrease of the efficiency of the solar cells. The electronic alignment at the interface between the different materials within the solar cell influences strongly the functionality and efficiency of the solarcell. The contact formation between the materials depends on the materials itself, but
also on the specific surface, e.g. adsorbates covering it. This work compares I-V characteristics of different solar cell device stacks with the respective energy diagrams. The investigation of the interface is mainly done by photoelectron spectroscopy, which is a
powerful method to determine the electronic alignment at the interface between different materials. The shape of the I-V characteristics of inverted organic solar cells oftendepends on the used metal oxide (which acts as electron transporting layer) within the
solar cell device stack. Typical electron transport layers are TiOx and aluminum doped
zinc oxide (AZO). Inverted organic solar cells with PC61BM:P3HT as absorber material
and AZO as electron transport layer show diode-like I-V characteristics, whereas solar
cells with TiOx as electron transport layer show S-shaped I-V characteristics. Using a
bilayer consisting of TiOx:AZO or AZO:TiOx as electron transport layer, only solar cells
where the TiOx forms the interface to PC 61 BM show S-shaped I-V characteristics. In
model experiments, C60 replaces PC61BM and the interface of C60 to TiOx and AZO is
determined by means of photoelectron spectroscopy. The interface energy diagram of
the TiOx/C60 interface displays a barrier for electron extraction, whereas the AZO/C60
interface does not. Interface experiments of C 60 with in situ (adsorbate free) and ex situ(adsorbate contaminated) cleaved anatase single crystals show the crucial influence of
adsorbates on the formation of the electronic interface between the metal oxide and
the organic absorber. Additional experiments show that the S-shaped I-V characteristics
with TiOx as electron transport layer transform into diode-like characteristics upon
illumination with UV light. In situ UV illumination of the TiOx/C 60 interface with UV
light induces changes of the band alignment, which result in a decrease of the electron
extraction barrier at the TiOx/C60 interface. Furthermore the reduction of the barrier is most probably caused by UV induced desorption of oxygen from the TiOx surface.
The second part focuses on fundamental investigations of the anatase (101) surface.
For this purpose, anatase single crystals are cleaved along the (101) surface plane by
pliers and a clean (101) surface, without any further preparation methods such as
sputtering and annealing, is obtained. Analyzing and comparing differently prepared
titania samples by normal and resonant photoemission reveals the existence of shallow
band gap states at the crystalline anatase surface. The origin of those shallow gap
states is assigned to step edges of monoatomic height at the anatase (101) surface and
respectively to the intersections of (101) surface planes of nanocrystalline anatase. In
water adsorption experiments, the adsorption kinetics of water onto the anatase (101)
surface are investigated in more detail.
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Wan-Chun-Wang and 王萬駿. "Rational Design and Investigation of photoelectric properties of Donor-acceptor Type Materials With Benzimidazole Cores." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/8vyrmq.
Full textAbstract:
碩士國立中央大學
化學學系
106
The development of renewable energy is crucial and imperative. Among all of them,solar cells are much anticipated. The efficiency of Perovskite Solar Cells (PSCs) made great progress very fast in short ten years. It’s a potential research topic due to low cost and easy to manufacturing. We hope that synthesis of donor-acceptor type hole transporting materials with benzoimidazole core are able to enhance absorption range of sunlight, besides we can regulate HOMO(Highest Occupied Molecular Orbital) and LUMO(Lowest Unoccupied Molecular) of the structures in order to match the band gap of Perovskite and improve efficiency of solar cell.
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Lo, Che-An, and 羅哲安. "Twisted donor π-conjugated acceptor thermally-activated delayed fluorescence materials for efficient Organic Light Emitting Diodes." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/00246819005114992085.
Full textAbstract:
碩士國立交通大學
應用化學系碩博士班
105
Since professor adachi propose the concept of 3rd generation OLED – thermally activated delayed fluorescence ( TADF ), the number of published papers about TADF become rapidly grow in recent years. Researchers vigorously to find and develop a new low cost, high efficiency, and stable TADF OLED material. In this thesis, we develop some novel compounds by using the D-π-A designed structure which is proposed by professor Adachi. We use the bulky DMAC with strong electron donating property as donor. The bulky DMAC will have steric hindrance effect when link to acceptor resulting a twisting angle between DMAC and acceptor. By linking the DMAC to different acceptors, we successfully synthesized new materials TRZPH2PHDMAC with TADF property with internal quantum efficiency of 87.8%.Meanwhile, all the devices prepared were greater than the maximum external quantum efficiencies (EQE) of 5% in fluorescent materials this suggests that the novel materials manage to utilize the triplet state energy back to singlet state to give a delayed fluorescent emission which is a high efficiency TADF material.
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Liu, Ken-Yen, and 劉耕硯. "Photophysics and Light-Induced Current Generation in Organic-Inorganic Hybrid Materials Incorporated with Donor-Acceptor Chromophores." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/95823381310910488915.
Full textAbstract:
碩士國立臺灣大學
化學研究所
92
Abstract There have been ever burgeoning interests on synthetic light harvesting systems to effectively mimic the natural process of energy transfer. In this thesis, different kinds of bis[(alkox)silane] moieties with different aromatic cores as donor and acceptor were empolyed. The organic-inorganic hybrids silica containing a combination of two to four kinds of chromophores were prepared by the sol-gel technique. When the hybrid material contained only one kind of the chromophore, self-quenching leading to red shift in the emission spectra in comparison with those of monomeric compounds measured in solution (aggregation may occur). Incorporation of a second chromophore into the system may segregate such kind of aggregation so that self-quenching might be avoided. The higher the donor concentration, the higher the emission intensity. These results are consistent with the light harvesting nature of our hybrid materials. Energy transfer can also occur in the hybrid material contained three and four kind of the chromophores. Furthermore, such system can show light-induced current generation property. Titanium oxide has been demonstrated to serve as an efficient electron acceptor in this system. When the hybrid material was prepared from TTIP and TEOS, a further enhancement of the photocurrent was obtained. The hybrid systems were used to fabricate Grätzel cells, and the efficiency reached around 1%。
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梁宗琦. "Supramolecular Assembly of H-Bonded Side-Chain Polymers Containing Conjugated Pyridyl H-Acceptor Pendants for Organic Electro-Optical Materials Applications." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/89746251710876582602.
Full textAbstract:
博士國立交通大學
材料科學與工程系所
97
First, two H-bonded acceptor polymers and were successfully prepared by polymerization of fluorescent pyridyl monomers, which were synthesized via Sonogashira coupling and Wittig-Horner reactions. Supramolecular side-chain and cross-linking polymers (i.e., H-bonded polymer complexes) were obtained by complexation of light-emitting H-acceptor polymers with various proton donor (H-donor) acids. Mesogenic and photoluminescent (PL) properties of light-emitting H-acceptor polymers can be adjusted not only by the central structures of the conjugated pyridyl cores but also by their surrounding non-fluorescent H-donor acids. Redder shifts of PL emissions in H-bonded polymer complexes occurred when the light-emitting H-acceptor polymers were complexed with H-donors having smaller pKa values. Second, a series of PL and liquid crystalline (LC) self-H-bonded side-chain copolymers consisting of pyridyl H-acceptors and isomeric acid H-donors (i.e., para-, meta-, and ortho-benzoic acids) were synthesized. Supramolecular H-bonded complexes were also obtained by mixing the photoluminescent H-acceptor homopolymer with isomeric H-donor homopolymers. The formation of H-bonds was confirmed by FTIR, DSC, and XRD measurements. Moreover, PL and LC properties of the H-bonded copolymers and complexes were affected not only by the H-bonding effect of the supramolecular structures but also by the acid-substituted positions of isomeric H-donors. In combination with different functionalized gold nanoparticles (which bear acid or acid-free surfactants), the emission intensities of nanocomposites containing self-H-bonded copolymer (bearing both H-acceptor and H-donor moieties) and non-self-H-bonded copolymer (bearing acid-protected moieties), respectively, were quenched to different extents by varying the concentration of gold nanoparticles. The copolymeric H-acceptors and surface-modified gold nanoparticles demonstrated diverse morphological and PL quenching effects on the supramolecular architectures of nanocomposites, which result from competition between the H-donors from the acid pendants on copolymers and the acid surfactants on gold nanoparticles. Third, this approach is exploring hydrogen-bonded (H-bonded) suparmolecular assembled behavior via both TEM and fluorescence quenching studies through organic solvent dissolving and evaporating processes. Different lateral methyl- and methoxy-substituted groups with pyridyl terminus of fluorescent side-chain polymers, it performed that the H-bonded interactions affect the fluorescence quenching effectively upon the addition of surface-modified gold nanoparticles bearing acid and acid-free surfactants in the fluorescence titrations experiments. We demonstrated that homopolymer PBOT1 has the highest Ksv constant in the compared fluorescent side-chain polymers. In addition, we established the exponential equation to predict Stern-Volmer constant in various pyridyl units of polymers from the experimental information. TEM studies displayed that interesting H-bonded suparmolecular behavior of addition into the carboxylic acid units of surface-modified gold nanoparticles. It is clearly observed that homogeneously gold nanoparticles distributions are on the fluorescent side-chain polymers. Thus, the TEM morphologies of H-bonded architectures demonstrate the versatility of the self-assembled processes in supramolecular nanocomposites of H-acceptor polymers and surface-modified gold nanoparticles. Finally, novel supramolecular side-chain polymers were constructed by complexation of H-acceptor polymers, i.e., side-chain conjugated polymers containing pyridyl pendants, with low-band-gap H-donor dyes (bearing terminal cyanoacrylic acids) in a proper molar ratio. H-bonded polymer complexes exhibited broad absorption peaks in the range of 440-462 nm with optical band-gaps of 2.11-2.25 eV. The PSC device containing H-bonded polymer complex blended with PCBM (1:1 w/w) gave the best preliminary result with an overall power conversion efficiency (PCE) of 0.50%, a short-circuit current of 3.17 mA/cm2, an open-circuit voltage of 0.47 V, and a fill factor of 34%.